Exam 6 infectious disease Flashcards
What is necrotizing fasciitis?
an infection leading to the necrosis of subcutaneous tissue; severe pain is common
How should you treat necrotizing fasciitis?
aggressively through surgery and IV antibiotics and fluids
What is acute infectious arthritis?
rapidly progressing joint infection, usually bacterial in origin
What is osteomyelitis?
Inflammation and destruction of bone caused by bacteria, mycobacteria, or fungi, causes localized bone pain and tenderness
What usually causes osteomyelitis?
contiguous spread or from open wounds
What is myositis?
Infection of the muscle that leads to muscle inflammation
What usually causes necrotizing fasciitis?
beta-hemolytic group A Streptococcus (S. pyogenes) and sometimes S. aureus
What do most patients have prior to a necrotizing fasciitis infection?
recent minor trauma, surgery, or varicella infection
What is the tree for S. pyogenes?
Gram+ cocci in chains, Catalase (-), Beta hemolytic, Bacitracin sensitive
What does necrotizing fasciitis typically present with clinicallY/
High fever and heart rate, altered mental status, low blood pressure, leukocytosis, positive blood cultures, will have rapid onset, high CRP and ESR, high WBC and banded neutrophils
What would you do to diagnose/treat necrotizing fasciitis initially?
gram stain wound, culture the wound, surgical debridement of necrotic tissue
What organism classically causes necrotizing fasciitis in immunocompromised individuals?
S. pyogenes
T/F: Erythrocyte sedimentation rate (ESR) is a non-specific indicator of tissue damage and inflammation?
True; it’s non-specific
When in ESR usually elevated?
Anemia, endocarditis, kidney disease, osteomyelitis, pregnancy
What is C-reactive protein involved in?
promotion of immune system through activation of the complement cascade; Upregulated due to cytokines released by leukocytes
when is CRP usually elevated?
bacterial infections, inflammation, acute rheumatic fever/arthritis, inflammatory bowel disease
Explain the classing system of synovial fluid
Synovial fluid should be clear/whitish. The more opaque it becomes the more it increases in class. Class IV has blood cells in it due to a ruptured synovial joint and its associated blood vessels
What usually causes acute infectious arthritis?
Typically S. aureus in older adults, N. gonorrhea in sexually active young adults
What do pts with acute infectious arthritis usually present with?
Rapid onset, personal history (sexually active/recent surgery), pain, limited ROM, synovial fluid analysis will be abnormal, positive blood cultures
What is the tree of Staphylococcus aureus?
Gran + cocci in clusters, Catalase (+), Coagulase (+)
What is the trea of Neisseria gonorrheae?
Gram- diplococci intracellular, Oxidase +, Only oxidizes glucose
What to pts with osteomyelitis typically present with?
Fever, high pulse, overlying skin is warm and red with multiple necrotic-appearing lesion, high ESR, CRP, WBC (some banded neutrophils)
What classically causes osteomyelitis of the spinal cord upon reactivation?
TB
How should osteomyelitis be treated
Antibiotic against specific pathogen
What are the main culprits of osteomyelitis?
S. aureus, Salmonella typhii, Pasteurella multocida
What can cause osteomyelitis from a cat bite?
Pasteurella multocida
What is the most common virulent factor of bacteria that cause osteomyelitis?
contain a capsule to prevent complement and antibodies from binding
Why do sickle cell patients more commonly get osteomyelitis due to salmonella?
expanded marrow leads to sites of infarction that act as foci for infection, gut becomes devitalized due to intravascular sickling to allow bacteria in, sickle cell pts have decreased bactericidal and opsonic activity against salmonella
What are the most common causes of myositis?
Clostridium perfringes, Staphylococcus aureus, Coxsackie A and B virus, Flavivirus (dengue fever), can also be caused by helminths Taenia solium and Trichinella spiralis
Where does trichinella spiralis typically infect humans
Due to eating undercooked meat of an animal that is infected (usually pigs), the parasite encysts inside the muscles
Where does trichinella spiralis reproduce?
inside the host’s intestine
What is the tree of clostridium perfringens?
Gram+ bacilli, spore forming, obligate anaerobe, non-motile
What organism is Gram+ cocci, Catalase + and Coagulase +?
S. aureus
What organism is Gram+ cocci, Catalase - and Beta hemolytic?
S. pyogenes
